Alk, salinity and Ph are probably the biggest things to test. Biggest thing is don't chase the numbers. The tank will somewhat balance itself, add about half of what you think you need at first until you get it all down good. My most current tank is just over 4 months old and already growing massive coraline. I personally don't think water changes are a super big deal, at least not weekly. Do you have any pics of your current setup?That’s good if it works for you. My tank is only 5, almost 6 months old, so I assume it needs weekly water change. And I’m also a beginner in this hobby even if I spent a year or 2 in research. I don’t have calcium, mag or po4 test kits, so the only thing that I can test is my ph, my salinity, nitrates, nitrites, alk, and ammonia.